The Colorado Clinical Nutrition Research Unit's Energy Balance Core Laboratory is in need of a new comprehensive metabolic monitoring system for mice (CLAMS-8M) from Columbus Instruments (Columbus, OH). An indirect calorimetry system is used to measure oxygen consumption and carbon dioxide production from which many aspects of energy metabolism can be determined including metabolic rate and respiratory quotient. The current 4 cage system is outdated, was originally built in 1996 and is heavily used. The computer system and interface boards in the current system only operate on Windows 98 and are not compatible with newer Microsoft operating systems and computers. The new indirect calorimeter will not only double our capacity to 8 cages, but will add other features such as real-time measurements of food and water consumption along with assessments of exercise, all of which our current system is unable to track. Having a larger capacity will also reduce the inter-experimental error. Additionally, the system will also be modified to be used with radioactive tracers to measure trafficking of fuels in tissue compartments and in carbon dioxide expiration. The caging for the new indirect calorimetry system will be enclosed in an environmental chamber so that lighting, temperature and humidity can be controlled precisely and allow investigators to conduct experiments at different environmental temperatures including: 1) thermoneutrality conditions (ambient temperature at which animals expends the least amount of energy to maintain body temperature) and 2) cold-exposure to further perturb the phenotype and detect differences which may not have been noticeable at standard ambient temperatures. The new indirect calorimetry system will be operated in accordance to regulations of an approved Animal Satellite Facility and will provide a great resource for users of the CNRU's core facilities, providing state of the art equipment for the increasing need for more comprehensive, reliable measurements of energy metabolism and fuel utilization in mice. PUBLIC HEALTH RELEVANCE: The Colorado Clinical Nutrition Research Unit's Energy Balance Core Laboratory is in need of a new piece of equipment that will be used to measure the metabolism of mice. With the information, we can perhaps achieve a better understanding of future treatments and prevention of obesity in humans.